In many industries, it is necessary to provide reliable seals that operate in extreme conditions including high pressures, high temperatures, and hostile chemicals. Conventional elastomeric seals may be damaged or fail completely under such conditions; therefore, metallic seals are the preferred solution for these extreme applications.
A conventional metallic C, V or U seal is often formed from sheet metal. The tolerances required to control installation forces can be difficult to achieve using sheet metal. In addition, parts manufactured from sheet metals are often formed from annealed material to facilitate the forming process. These parts would then require additional processing in the form of heat treatment (such as solution heat treatment followed by precipitation hardening) to achieve optimum material strength. During heat treatment, the seal typically experiences dimensional changes that are often difficult to predict as the magnitude of the changes are proportional to the residual stresses in the formed part. Also, the shape of the typical formed C, V or U metal seal is difficult to machine from pre-hardened materials due to the inherent flexibility of the cross sectional geometry. Accordingly, there is a need for an annular seal that can be manufactured without the stress and tolerance issues common to traditional C, V or U shaped seals manufactured with traditional sheet metal processes. As such, a cross section geometry that can be machined from hardened materials is needed.
In some critical applications redundant seals may be used. Stacking or nesting traditional C, V or U shaped seals for sealing redundancy can result in unpredictable performance. Furthermore, there exists a need for an annular seal that can be stacked or nested for redundant sealing without distorting the cross section of the seal. A stacked arrangement could be used in bi-directional pressure applications. A nested arrangement could be used in a uni-directional pressure application.